Mana Drain and Mind Twist

[Jhaggs]

This is an old question but a situation arose in a card store tournament that I was playing in and I wanted to get an exact explaination of this interaction.  I wasn't involved in the match so I didn't chime (probably should have) but I'm not sure I could articulate the correct ruling as a normal DCI judge would have.

Player 1 casts a mind twist for 5.
Player 2 casts Mana Drain and the drain resolves.

Player 2 claims that he has 6 free mana on his next main phase.
Player 1 protests claiming that the Drain is set at 1 free mana.

The store owner interjects and rules in favor of player 2 citing this ruling:

203.Ruling.1 - If a cost has an "X" in it, the mana cost equals the amount announced as part of playing the spell or ability while it is on the stack, but if the card in any other zone, X is treated as zero. [D'Angelo 2003/09/08] See Rule G24.1a.

What is the best way to resolve this dispute?

[DEA]

that's a nice ruling
too bad drain doesn't reference the X on the card, but the CMC of the spell on the stack, which is SIX when it is being cast

[Limbo]

DEA has a very short but correct answer. If you want a little more explanation, maybe you want to look here (search function / opening eyes anyone?). The search function isn't invented for nothing...